Automate running DB-tests with an extra database run_tests.sh allows to run database tests easily without affecting other existing databases and on a clean basis. Because roles are cluster-wide, they cannot be easily droped and recreated without affecting other databases. Thus, moved their creation to roles.sql and in passing removed unnecessary role 'gemma'.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/schema/roles.sql	Thu Jul 12 16:30:01 2018 +0200
@@ -0,0 +1,6 @@
+--
+-- Primary GEMMA roles
+--
+CREATE ROLE waterway_user;
+CREATE ROLE waterway_admin IN ROLE waterway_user;
+CREATE ROLE sys_admin CREATEROLE BYPASSRLS IN ROLE waterway_admin;